They used a "magic trick" to reverse a person's responses to such moral issues as "Large-scale governmental surveillance of e-mail and Internet traffic ought to be forbidden as a means to combat international crime and terrorism", by switching "forbidden" to "permitted" when the subject turned the page of the questionaire. When asked to read back the questions and answers, about half of the subjects did not detect the changes, and a full 53% of participants argued unequivocally for the opposite of their original attitude in at least one of the manipulated statements.Link to Original Source